Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study evaluated the effect of pH on Porphyromonas gingivalis lipopolysaccharide (LPS) affinity for polymethyl methacrylate, polyethyl methacrylate, and polyethyl and polyisobutyl methacrylate resins. Specimens were exposed to 1,010 endotoxin units LPS in potassium phosphate buffer at pH 6, pH 7, or pH 8. Control specimens were incubated in LPS-free water. Sequence I evaluated LPS uptake and release from resin when exposure and elution pH were identical, whereas Sequence II evaluated LPS release from resin when elution pH differed from exposure pH. A slightly acidic pH decreased LPS affinity for all resins compared to pH 7. A slightly alkaline pH increased LPS affinity for the polyethyl methacrylate resin but decreased LPS affinity for the others compared to pH 7. The pH may affect resin-LPS affinity by altering LPS molecular charge.
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PMID:Effect of pH on Porphyromonas gingivalis endotoxin affinity for resins. 895 58

We tested the hypothesis that expression of inducible nitric oxide synthase (NO-synthase) in response to endotoxin (lipopolysaccharide) produces activation of potassium channels. Contraction of the rat thoracic aorta in response to phenylephrine was measured in vitro after treatment in vivo for 15 hr with vehicle (control) or lipopolysaccharide (10 mg/kg i.p.). Impaired contraction in response to phenylephrine was used as an index of inducible NO-synthase expression, and activation of potassium channels was examined with specific inhibitors. Contraction in response to 10(-5) M phenylephrine (expressed as a percentage of contraction in response to 85 mM KCI) was markedly impaired in lipopolysaccharide-treated rats, compared with control (15 +/- 5% vs. 131 +/- 10%, P < .05, mean +/- S.E.). Expression of inducible NO-synthase mRNA in the vessel wall in lipopolysaccharide-treated rats was confirmed using reverse transcription-polymerase chain reaction. Contraction of the aorta in lipopolysaccharide-treated rats was restored to normal by 0.3 mM aminoguanidine (an inhibitor of inducible NO-synthase). Contraction of the aorta in response to phenylephrine, which was inhibited by lipopolysaccharide, was not affected by glibenclamide (an inhibitor of ATP-sensitive potassium channels) but was increased 2-fold (P < .05) by iberiotoxin (50 nM), an inhibitor of Ca(+2)-dependent potassium channels. Relaxation of the aorta in response to sodium nitroprusside, an exogenous donor of nitric oxide, and 8-bromo-cyclic GMP was also inhibited by iberiotoxin. These findings suggest that nitric oxide produced by vascular expression of inducible NO-synthase activates calcium-dependent potassium channels and that this mechanism may contribute to impaired vasoconstrictor responses during sepsis.
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PMID:Vascular expression of inducible nitric oxide synthase is associated with activation of Ca(++)-dependent K+ channels. 896 77

An antigen extracted from Dichelobacter nodosus with potassium thiocyanate (KSCN) is currently used in enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of ovine footrot, but the test lacks specificity in mature sheep. Other antigens were therefore evaluated for use in this test. Structural components of the cell envelope of D. nodosus including outer membrane, cytoplasmic membrane, lipopolysaccharide and pilus and extracellular proteases were purified from cultured D. nodosus while recombinant membrane proteins, protease and pilus antigens were also evaluated. Many antigenic components of D. nodosus participated in reactions in ELISA that were not specific for infection with D. nodosus and apart from pilus, none of the antigens resulted in improved specificity of the ELISA. Using a positive-negative cut-off to yield sensitivity of 70%, ELISA using pili from cultured D. nodosus serogroup A had a specificity of 98.3% compared with 89.7% for the ELISA with KSCN-extract as antigen (P < 0.001). Recombinant pili morphogenetically expressed in Pseudomonas aeruginosa were unsuitable for use in ELISA due to copurification of Pseudomonas antigens to which apparently healthy sheep directed antibodies. The application of ELISA with D. nodosus pilus as antigen in footrot control programs is discussed.
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PMID:Antigens for serological diagnosis of ovine footrot. 910 Mar 27

Somatostatin infusion causes hyperkalemia in healthy subjects and in some animal models. The purpose of this investigation was to determine what effect octreotide has on potassium homeostasis during serious illness and if there is a dose-response relationship. Sixty-six male Sprague-Dawley rats (185-225 g) were randomized to receive parenteral nutrition (PN) only, PN plus continuous infusion of Escherichia coli lipopolysaccharide (LPS), or PN plus LPS plus octreotide 10, 100, or 1000 micrograms/kg/day for 48 hours. Before randomization all animals received isocaloric, isonitrogenous, isokalemic PN. A 24-hour urine was collected and a blood sample was taken at the end of the study immediately before euthanization. Data were analyzed by ANOVA and Duncan's multiple range test. Nonhemolyzed serum samples from 50 rats were available for study. Serum potassium concentrations were in the normal range for rats and did not differ significantly among the groups: 5.97 +/- 0.86, 5.96 +/- 1.58, 5.78 +/- 1.48, 5.79 +/- 1.67, 5.35 +/- 0.78 mEq/L, respectively. No differences among groups were found for fractional excretion of potassium or serum creatinine concentration. Octreotide administration in escalating dosages does not cause hyperkalemia in endotoxemic rats given intravenous potassium at a constant rate by PN.
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PMID:Octreotide and potassium homeostasis. 916 58

Melatonin, the chief secretory product of the pineal gland, was recently found to be a free radical scavenger and antioxidant. This review briefly summarizes the published reports supporting this conclusion. Melatonin is believed to work via electron donation to directly detoxify free radicals such as the highly toxic hydroxyl radical. Additionally, in both in vitro and in vivo experiments, melatonin has been found to protect cells, tissues and organs against oxidative damage induced by a variety of free radical generating agents and processes, e.g., the carcinogen safrole, lipopolysaccharide, kainic acid, Fenton reagents, potassium cyanide, L-cysteine, excessive exercise, glutathione depletion, carbon tetrachloride, ischemia-reperfusion, MPTP, amyloid beta (25-35 amino acid residue) protein, and ionizing radiation. Melatonin as an antioxidant is effective in protecting nuclear DNA, membrane lipids and possibly cytosolic proteins from oxidative damage. Also, melatonin has been reported to alter the activities of enzymes which improve the total antioxidative defense capacity of the organism, i.e., superoxide dimutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase, and nitric oxide synthase. Most studies have used pharmacological concentrations or doses of melatonin to protect against free radical damage; in a few studies physiological levels of the indole have been shown to be beneficial against oxidative stress. Melatonin's function as a free radical scavenger and antioxidant is likely assisted by the ease with which it crosses morphophysiological barriers, e.g., the blood-brain barrier, and enters cells and subcellular compartments. Whether the quantity of melatonin produced in vertebrate species is sufficient to significantly influence the total antioxidative defense capacity of the organism remains unknown, but its pharmacological benefits seem assured considering the low toxicity of the molecule.
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PMID:Pharmacological actions of melatonin in oxygen radical pathophysiology. 919 81

Here the effect of glycine on intracellular Ca2+ concentration ([Ca2+]i) in cultured Kupffer cells stimulated with lipopolysaccharide (LPS) was investigated to assess the possibility that they contain a glycine-gated chloride channel. LPS (10 micrograms/ml) increased [Ca2+]i rapidly, with peak values reaching 307 +/- 29 nM. Glycine (1 mM) prevented this increase nearly completely. Low concentrations of strychnine (1 microM), a glycine receptor antagonist, reversed the inhibitory effect of glycine completely; however, high concentrations of strychnine (1 mM) mimicked glycine. The effects of glycine and high-dose strychnine were prevented when cells were incubated in chloride-free buffer. Furthermore, potassium (25 mM) and LPS depolarized the Kupffer cell plasma membrane, whereas glycine caused hyperpolarization and prevented depolarization due to potassium and LPS. Moreover, tumor necrosis factor-alpha (TNF-alpha) production in cultured Kupffer cells due to LPS was decreased significantly by glycine. Therefore, it is concluded that Kupffer cells contain a glycine-gated chloride channel similar to that described previously in the central nervous system. Prevention of increases in [Ca2+]i due to LPS by activation of chloride influx reduced synthesis and release of toxic mediators by Kupffer cells.
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PMID:Kupffer cells contain a glycine-gated chloride channel. 922 96

Melatonin's actions in organisms are more widespread than originally envisaged. Over three decades ago, the changing pattern of nocturnal melatonin production was found to be the signal for the annual cycle of reproduction in photoperiodic species. Since then, melatonin's actions also have been linked to circadian rhythms, immune function, sleep, retinal physiology and endocrine functions in general. In recent years, however, the sphere of influence of melatonin was further expanded when the indole was found to be an effective free radical scavenger and antioxidant. Free radicals are toxic molecules, many being derived from oxygen, which are persistently produced and incessantly attack and damage molecules within cells; most frequently this damage is measured as peroxidized lipid products, carbonyl proteins, and DNA breakage or fragmentation. Collectively, the process of free radical damage to molecules is referred to as oxidative stress. Melatonin reduces oxidative stress by several means. Thus, the indole is an effective scavenger of both the highly toxic hydroxyl radical, produced by the 3 electron reduction of oxygen, and the peroxyl radical, which is generated during the oxidation of unsaturated lipids and which is sufficiently toxic to propagate lipid peroxidation. Additionally, melatonin may stimulate some important antioxidative enzymes, i.e., superoxide dismutase, glutathione peroxidase and glutathione reductase. In in vivo tests, melatonin in pharmacological doses has been found effective in reducing macromolecular damage that is a consequence of a variety of toxic agents, xenobiotics and experimental paradigms which induce free radical generation. In these studies, melatonin was found to significantly inhibit oxidative damage that is a consequence of paraquat toxicity, potassium cyanide administration, lipopolysaccharide treatment, kainic acid injection, carcinogen administration, carbon tetrachloride poisoning, etc., as well as reducing the oxidation of macromolecules that occurs during strenuous exercise or ischemia-reperfusion. In experimental models which are used to study neurodegenerative changes associated with Alzheimer's and Parkinson disease, melatonin was found to be effective in reducing neuronal damage. Its lack of toxicity and the ease with which melatonin crosses morphophysiological barriers and enters subcellular compartments are essential features of this antioxidant. Thus far, most frequently pharmacological levels of melatonin have been used to combat oxygen toxicity. The role of physiological levels of melatonin, which are known to decrease with age, is being investigated as to their importance in the total antioxidative defense capacity of the organism.
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PMID:Melatonin in relation to cellular antioxidative defense mechanisms. 928 72

The S-layer of Caulobacter is a two-dimensional paracrystalline array on the cell surface composed of a single protein, RsaA. We have established conditions for preparation of stable, soluble protein and then efficient in vitro recrystallization of the purified protein. Efficient recrystallization and long range order could not be obtained with pure protein only, though it was apparent that calcium was required for crystallization. Recrystallization was obtained when lipid vesicles were provided, but only when the vesicles contained the specific species of Caulobacter smooth lipopolysaccharide (SLPS) that previous studies implicated as a requirement for attaching the S-layer to the cell surface. The specific type of phospholipids did not appear critical; phospholipids rather different from those present in Caulobacter membranes or archaebacterial tetraether lipids worked equally well. The source of LPS was critical; rough and smooth variants of Salmonella typhimurium LPS as well as the rough form of Caulobacter LPS were ineffective. The requirement for calcium ions for recrystallization was further evaluated; strontium ions could substitute for calcium, and to a lesser extent, cobalt, barium, manganese and magnesium ions also stimulated crystallization. On the other hand, nickel and cadmium provided only weak crystallization stimulation, and zinc, copper, iron, aluminum ions, and the monovalent potassium, sodium, and lithium ions were ineffective. The recrystallization could also be reproduced with Langmuir-Blodgett lipid monolayers at an air-water interface. As with the vesicle experiments, this was only successful when SLPS was incorporated into the lipid mix. The best method for RsaA preparation, leading to apparently monomeric protein that was stable for many months, was an extraction with a low pH aqueous solution. We also achieved recrystallization, albeit at lower efficiency, using RsaA protein solubilized by 8 M urea, a method which allows retrieval of protein from inclusions, when expressed as heterologous protein in Escherichia coli or when retrieved as shed, precipitated protein from certain mutant caulobacters. In summary, the clarification of recrystallization methods has confirmed the requirement of SLPS as a surface attachment component and suggests that its presence in a membrane-like structure greatly stimulates the extent and quality of S-layer formation. The in vitro approach allowed the demonstration that specific ions are capable of participating in crystallization and now provides an assay for the crystallization potential of modified S-layer proteins, whether they were produced in or can be secreted by caulobacters.
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PMID:Factors controlling in vitro recrystallization of the Caulobacter crescentus paracrystalline S-layer. 933 82

To determine which factors are useful for the risk assessment of man-made fibers, we examined the gene expression of proinflammatory cytokines, growth factors, manganese superoxide dismutase (MnSOD), and inducible nitric oxide synthase (iNOS) in mineral fiber-exposed rats by means of reverse transcription-polymerase chain reaction (RT-PCR). Male Wistar rats received a single intratracheal instillation of either saline (control) or two types of fibers (2 mg of Union Internationale Centre le Cancer (UICC) chrysotile or alumina silicate refractory ceramic fiber [RCF]). Expression of interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), platelet-deriving growth factor-A, (PDGF-A), platelet-deriving growth factor-B (PDGF-B), transforming growth factor beta 1 (TGF-beta 1), basic fibroblast growth factor (bFGF), MnSOD, and iNOS mRNA from lung and lipopolysaccharide (LPS)-stimulated alveolar macrophages (AM) were assessed by RT-PCR. Among these factors, IL-1 alpha, TNF-alpha, IL-6, bFGF, and iNOS would be the possible parameters for the risk assessment of fibers. In a follow-up study, we investigated the time course (3 days, 1 week, 1 month, and 3 months) of expression of IL-1 alpha and TNF-alpha by LPS-stimulated AM exposed to mineral fibers in vivo. Male Wistar rats were instilled intratracheally with saline or fibers (2 mg of Union Internationale Contre le Cancer UICC crocidolite or potassium octatitanate whisker [TW]). The expression of IL-1 alpha mRNA by fibers was greatest in TW, crocidolite, chrysotile, and RCF-instilled rat AM, in that order. The increase of IL-1 alpha and TNF-alpha mRNA in AM peaked at 1 month and 3 days after exposure to crocidolite or TW, respectively. The expression of IL-1 alpha by fibers (crocidolite, chrysotile, TW, and RCF) may be a good indicator of the pathologic potential of fibers.
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PMID:Effects of mineral fibers on the expression of genes whose product may play a role in fiber pathogenesis. 940 Jul 19

Monocyte chemotactic protein-1 (MCP-1) is a proinflammatory cytokine that attracts and activates specific types of leucocytes. The purpose of this work was to analyse the generation of MCP-1 and mRNA transcript in a model of chronic inflammation using a granulomatous tissue induced by potassium permanganate (KMnO4; water soluble crystals). The data presented here shows that MCP-1 is generated in granuloma tissue and its level was strongly increased by i.p. injections of lipopolysaccharide (LPS) and inhibited in rats treated with injections of dexamethasone, 18 hr before the animals were killed. In histological studies LPS and dexamethasone increased and decreased, respectively, the recruitment of mononuclear cells in the granuloma tissue compared with the control granulomas from phosphate-buffered saline (PBS)-treated animals. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for mRNA extraction and cDNA synthesis. mRNA MCP-1 was significantly produced in the granuloma tissue of untreated animals, an effect increased by LPS and inhibited by dexamethasone, compared with the controls. Moreover, MCP-1 protein was found in the supernatant from homogenized granuloma tissues and the levels of MCP-1 were higher in the LPS-treated animals, while they were lower in the dexamethasone group, compared with the granulomas from the PBS-treated groups (control). The generation of MCP-1 was also found in minced granuloma tissue incubated for 18 hr (overnight) from treated (LPS or dexamethasone) and untreated (PBS) rats. When LPS was added in vitro for 18 hr to the controls and treated animals the production of MCP-1 was further increased except in the dexamethasone group (P > 0.05). Analysing blood serum from LPS, dexamethasone or PBS-treated rats, we found that MCP-1 was also present. The level was higher in the LPS group and lower in the dexamethasone group, compared with the control (PBS). In these studies we show for the first time that MCP-1 transcript and translation is generated in chronic experimental inflammatory tissue, an effect inhibited by dexamethasone.
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PMID:Augmentation of monocyte chemotactic protein-1 and mRNA transcript in chronic inflammatory states induced by potassium permanganate (KMnO4) in vivo. 941 40


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